Buick will debut a new 2018 Regal in April that analysts say will be based significantly on the new Opel Insignia, to be unveiled Tuesday at the Geneva International Motor Show.

It’s likely the new midsize Regal could come in a wagon version for the U.S. market, some analysts say.

Opel will use the Geneva show to debut its second-generation Insignia Grand Sport and Sports Tourer wagon, which are built on a new architecture. The Insignia is built in Opel’s Rüsselsheim factory in Germany, the location many analysts believe also will build the Regal for the U.S. market.

On Monday, General Motors Co. and French carmaker PSA Group announced PSA will buy GM’s European business Opel for $2.2 billion. The companies said the deal, expected to close late this year, includes maintaining existing supply agreements for Holden and certain Buick models.

GM President Dan Ammann would not name the Buick and Holden vehicles that are part of the agreement or how long they will be built. The Holden brand is sold in Australia.

The Regal is built at General Motors Co.’s Oshawa Assembly Plant in Canada, but analysts believe production of the current version will end there this summer and that GM will use Europe or China as the production source for the new generation for the U.S. market. They expect to see the next generation Regal on sale in the U.S. later in the year.

Former GM CEO Dan Akerson in 2013 said GM planned to pair product development of Opel and Buick together, and industry insiders believe much of the Regal will be based off the Insignia. The Buick Cascada convertible on sale here now is a rebadged Opel Cascada. Both are built in Poland.

And in March 2014, Opel said its Rüsselsheim plant would build a future Buick model to be sold in the U.S., only stating that the production launch would be in the second half of the decade.

GM reintroduced the 2011 Regal — based on the Insignia in Europe — in the U.S. in 2010 after a production lull, and refreshed it for the 2014 model year. U.S. sales totaled just less than 20,000 last year, up 1.7 percent. Sales through the first two months of the year, however, are down 53.7 percent compared to the same months in 2016.

Buick will show the new Regal on April 4 at its Design Dome at the Warren Tech Center, a week ahead of the New York International Auto Show. Analysts expect to see Buick’s newly redesigned Enclave SUV at the New York show.

Buick spokesman Stuart Fowle would not comment on where the new Regal will be built: “It’ll be on sale later this year and will continue to build on its role of our sportiest vehicle with the youngest customer base in the lineup.”

Dave Sullivan, manager of product analysis for AutoPacific, said he believes the Regal will be built in Germany.

LMC Automotive believes Buick will do away with the Regal sedan for the U.S. market and instead offer a hatchback and wagon version, said Bill Rinna, senior manager of North American forecasts for LMC Automotive. LMC believes GM will source both versions from Germany.

Fowle would not comment on body styles for the next-generation Regal. Photos of the rear of the Insignia show a large, glass back window that appears connected to the trunk, indicating the whole back may open, adding to utility.

LMC Automotive believes a new Regal hatchback will begin production in Germany soon and reach showrooms in the U.S. in late summer, with a wagon beginning production a few months later and arriving here in the fall. The Regal wagon could represent about 30 percent of Regal’s annual U.S. sales, Rinna said.

Buick has not had a wagon in its U.S. lineup since the mid-1990s with the Century and Roadmaster.

GM in late 2015 filed trademark applications for the Tourx and Regal Tourx names. Sullivan expects the Regal wagon will be called the Tour X, and says a wagon would give Buick something that customers couldn’t get from other GM brands.

GM’s global product development chief Mark Reuss has indicated he would like an affordable, sporty wagon for U.S. showrooms.

“He will get it with the Regal wagon,” Rinna said in an email. “Unfortunately for Buick, and although they have never been tremendously popular in the U.S., it will arrive at a time when wagons are getting further lost in the SUV offensive.”

Some analysts, including Joe McCabe, president and CEO of AutoForecast Solutions LLC, think GM could chose to bring the Regal to the U.S. from China. GM builds the Regal for the Chinese market in China.

“Unions may balk at that,” McCabe said.

GM already imports the Buick Envision SUV from China; the Cadillac CT6 plug-in also will come from China this spring. The United Auto Workers union has criticized GM for importing those vehicles from China. President Donald Trump also has threatened to slap tariffs on imports coming from Mexico and China.

Opel says the new Insignia will be available with an eight-speed automatic transmission or six-speed manual. It will weigh 385 pounds less than the current sedan. The new Insignia will be offered with a 1.5-liter turbo four-cylinder and 2-liter turbo four-cylinder gasoline engines, and 1.6-liter and 2-liter diesels. It’s unclear if GM will use the same engines or transmissions on the Regal here.

A 2-liter turbo or 2.4-liter four-cylinder gas engine is under the hood of the current Regal in the U.S.